This invention relates to dot matrix printer systems, and more particularly to control systems for facilitating operator selection of a wide variety of functions and operating modes in a serial character printer.
Modern dot matrix printers provide features and versatility that cannot readily be duplicated by other mechanical printer types, because the dot matrix format enables virtually arbitrary placement of dots to form characters, patterns, graphs and other representations. The most used form is the serial character printer, which can be manufactured at suitably low cost for usage with modern personal computers and microcomputers.
Such printers now commonly use the capability for almost arbitrary dot placement to provide many different print formats at different speeds. The individual character cell (originally formed by a typically 5.times.7 matrix) is now varied from a relatively low density matrix, used in draft mode printing, to a much higher density letter mode. Moreover, type fonts can be changed by using different software or ROMs, and different languages can be accommodated. Characters can be reduced or expanded in size and inter-cell spacings can also be manipulated. Special printing features, such as underlining, bold characters, subscripts and superscripts are also incorporated.
Easy control of margins, page setup and paper movement functions for both cut sheet and pinfeed paper are sought. There is much more to the modern printer system, however, since it generally incorporates its own central processor unit and is capable of quite complex functions. It is therefore quite common to provide a variety of communications options, as in responding to different bit rates, handshaking protocols, serial and parallel inputs and even emulating other machines. Printing in different colors is often a desirable feature. In addition, different users and different applications may require certain standard settings, and for these it should be unnecessary to proceed through an entire setup procedure. Instead, the chosen settings should be effective upon startup or with a simple selection procedure. Operation of these systems has therefore become increasingly complex as the number of features and control functions have increased. The usual design response has been to provide a wide variety of selection switches and devices, both on the control panel for the unit and within the unit itself.
An example of a modern serial character printer having multiple controls is provided by the AMT Office Printer, which has an array of pushbuttons for controlling individual mechanical and electronic functions. It includes internal DIP switches which must be accessed by opening the cover of the machine to control communication configurations, for example. While this system has gained wide acceptance and is at the level of the current state of the art, it is desirable to provide even more functions and controls. This would make the tasks of the printer system operator unduly complicated if the same control and display approach were to be utilized. Only a long instructional period would suffice to enable the operator to readily determine the options available, to set parameters and choose modes. Furthermore, it is difficult to organize a system such that more features can be added, or features can be revised, without inordinately increasing the cost of the electronics or the mechanical part of the system. The entire menu must be available for changing parameters but the most often used parameters should be readily changeable.
There are many techniques and systems available for providing multi-function controls. Remote control devices for video and audio equipment have particularly been designed for ease of operation and clarity of interaction. These typically have an array of buttons and function with a control system which concurrently provides a display of elements in a changing sequence or menu. One such panel control is the Casio Model HT-700 electronic keyboard synthesizer in which many pushbuttons are disposed in different positions for controlling different functions, and a rotary dial is used in one mode to control tempo and in another mode to control sequencing of numbers on a display in order that different control functions can be selected. Another example is the Sony Model RMT-193 remote commander assembly for controlling VCR and TV systems. In this arrangement the remote controller has a matrix comprising a number of buttons, together with a split ring rotary dial system used as a "jog/shuttle" control in one mode, since the different parts can be used either to change the speed of scanning in a continuously variable fashion in either direction, or frames can be advanced one at a time. In the other mode of operation, the control can be used to scan through channels or scan through time settings in order to program the unit to function in accordance with a particular schedule. A third unit, the control for a CD player manufactured by Technics, uses a rotary dial to control the selection of tracks, perform queuing operations and shift the reproducing mechanism to different parts of tracks. These systems are too limited and specialized to be adaptable to the much greater and unique demands of a modern serial character printer, but they do establish standards for ease of use and simplicity of operation.